6 replies to this topic

[coyttl]

Hey all! Been quiet around here the last few months - mainly because I haven't been driving the Mini. However, despite it being winter, the weather was nice the last few days, so I decided to go motoring.

I wanted to get thoughts on some odd happenings. The Mini sat in storage for the last 2 months, and when I tried to start it, battery was dead. (Idiot me forgot to disconnect it.) So I jump start it just fine. Idles fine, operates normally. Drive it to the nearest petrol station and fill it up. After I fill it up and I'm getting ready to leave, the idle drops to under 500. It doesnt' SOUND like it's going to die, but sounds ROUGH. Pressing on the throttle it speeds up fine, but then drops back down really low. So, then I head down to my office. There's about a 12 mile drive on the highway, ~70MPH. It was constant - no slowing the entire way. I get off the roadway and push the clutch in. The idle bounces - between 2k and 2.5k. It's acting as if the throttle's being held open and then at 2.5k the ECU turns off the injector. However, unlike me holding the throttle open manually, the rise - from 2k to 2.5k is slow. And the longer I let it sit, the slower the rise becomes. Eventually, it stops, hovering around 2.2-2.3k. I stop and open up the bonnet and take the air intake off. The throttle appears closed. Now here's the other odd thing. A few times, I could step on the brake and release the clutch, 'forcing' the idle down to 1k, and it would then stay there. (Sometimes, however, doing this would result in it bouncing back up to 2k.)

The next day I start it up, and it immediately starts out idling really low - under 500 and sounding rough. It does NOT sound like it's missing on a spark, but I'm not 100% sure on that. Gun it a few times, still idles really low. Go out motoring, and it drives fine - no apparent loss of power. After a little bit of driving - about 5 miles at 45-50mph, it idles fine, and does so the rest of the day (~20 miles total.)


So I'm kinda thinking SOME sensor is starting to die, but not sure where to start playing around. The last issue I had was the fuel pump cutting off, and that was fixed by replacing the fuseblock.

Thoughts?
Thanks in advance!
Mike.

[Sprocket]

Unusualy odd one that I am not sure where to start.

I would look over the simple things first such as the vac lines, make sure there is no fuel trapped in those, make sure they are all connected properly. Also make sure the engine can get up to temperature, remember the needle on the gauge sould sit at the half whay mark.

One other thing to consider is that modern fuels left to stand for periods longer than 2 weeks can and does become stale.

Throttle closed and an idle of 2k+ = air leak some where, Vac lines prime suspect. However do not consider a sticking throttle cable out of the question.

[sir Jake the brit]

sorry deleted that didnt pay full attention, didnt notice you were on about the spi!!

Edited by sir Jake the brit, 30 December 2008 - 01:38 AM.

[Sprocket]

Yours is MPi this is SPi, its not the same and there is no wonder fix

[coyttl]

Hey guys, thanks.

A couple notes - it could be a vac line, I'll have to check it. I know it's not the MAP line to the ECU - I've lost that one a couple times, and it never affected the idle speed. (DID make it run super-duper rich tho!)

Now, for the temperature, that's always been funky. The gauge never gets above 1/4 of the way. (Halfway between Middle and "C".) At first, a year ago or so, it never got above "C". I since then changed the thermostat to one that was MUCH warmer one (98C) and since then has onyl made it 1/4 the way. I believe I need a new temp sensor. However, this is not new, and was not bipolar idling before when the temp was this way.

I'll check all my hoses tomorrow at work, and will let ya'll know if I find anything.

[coyttl]

Okay, quick update -

The red vacuum hose that goes to the air filter housing (now detached because I have a K&N intake) has an odd crack in it. I'll be replacing it soon, and we'll see if that has any effect.

Also, today I drove the same route as my first trip in the original post, and this time when I got off the motorway, the idle dropped to 2k, and took about 10 seconds to sssllooowwly drop down to ~1k RPM.

Cheers all!
Mike.

[coyttl]

Hey all, rehasing an old issue. Any and all thoughts are welcome!

The aforementioned odd-idle issue didn't happen for quite a while. While I didn't drive it as much, when I did it did not happen.

Then, after driving about 15 miles @75mph (3500rpm) I stopped to fill up. Filled her up all the way, and started her. She immediately started the odd-revving. (My thought at this time was that I over-filled it, and the evap systam was backflowing or some such. However, it continued after the tank got down to half-full.)

Again, to rehash - then the idle drops from high up, it'll drop to about 2k, then increase to 2.5k-3k and then drop back to 2k. It sounds EXACTLY as if I had manually held the throttle open with the throttle switch closed. (The only difference is that I'm not holding it open, and the rising idle takes 1-2 seconds, whereas if you held the throttle open, it'd happen MUCH quicker.) Over time - about 50 miles - the rate at which it increases from 2k to 2.5-3k will decrease, taking it up to 3-5 seconds to rise up to 2.5-3l before falling. Then, after that, it will just try to idle at between 2k to 2.5k, without increasing.

The first times it happened, if I held the clutch in to 'force' the idle down to 1k, it would then hold there. Recently, however, this trick didn't work - as soon as I'd push in the clutch, it'd jump from 1k to 2k to 2.5k and then drop down, repeating.

Now, add to that that I've been driving the Mini daily for the last week. Sometimes long trips (50/100 miles) sometimes shorts (2 miles). Ran fine other than the occasional idle issue above. Oh,t hat's right, it doesn't happen all the time - it's intermittent, darnit.

Last night, however, as I was speeding up to get on the motorway I kept her in third and got my RPMs up to 5 or 6, and noticed that for a quick minute (half a second) I lost some power. It continued down the road for 40 miles or so, sometimes barely noticeable, sometimes very noticeable.

Now, if I put the two issues together, I'd swear that the spark advance was what is fouling up. (Too much in idle, therefore speeding the engine up until the injector cuts off, then re-engaging. And NEEDING it advanced and not getting it more recently while on the highway.)

I realize this all points to vacuum line. The only thing I'm having a hard time understanding is.. why? The last time I lost a vacuum line, I had no problems speeding up under torque, but idling was really rough, not sped-up like it is now.

I pulled my fuel-trap and the black/black green vacuum lines. All seemed okay, except the elbow joint between ECU and Fuel trap was kind of loose. I'm going to replace that now and take her out for a test drive, see if it helped at all.

I have a backup ECU that I can try, and if fixing the elbow doesn't help that'll be next.

However, any other comments are appreciated. I'll entertain anything at the moment!

[ Edit: Oh, I forgot. The idling issue DID start after I put in the K&N cold air intake. However, it did not happen at the SAME TIME. It probably appeared about 6 months afterwards. The K&N has the air temp sensor in it, however, it is not positioned near the intake pipe. But it never was, either. ]

[ Edit 2: Okay, after replacing the elbow and taking her on a strenuous drive, that loss of power issue is fixed. I didn't drive it long enough to determine if the rev-idle issue is also fixed, however. ]

Edited by coyttl, 18 June 2009 - 06:25 PM.